code: def __init__(self, loader, stop_after=None):
      self.loader = loader
      self.dataset = loader.dataset
      self.stream = ch.cuda.Stream()
      self.stop_after = stop_after
      self.next_input = None
      self.next_target = None
  
imports: import torch
  import shutil
  import dill
  import os
  from subprocess import Popen, PIPE
  import pandas
  from PIL import Image
  from .None import constants
label_desc: Use image node_id 1 to create a new DataPrefetcher object  with example: obj = DataPrefetcher(loader, stop_after)